title: Role of the vaccinia virus O3 protein in cell entry can be fulfilled by its Sequence flexible transmembrane domain.
abstract: The vaccinia virus O3 protein, a component of the entry-fusion complex, is encoded by all chordopoxviruses. We constructed truncation mutants and demonstrated that the transmembrane domain, which comprises two-thirds of this 35 amino acid protein, is necessary and sufficient for interaction with the entry-fusion complex and function in cell entry. Nevertheless, neither single amino acid substitutions nor alanine scanning mutagenesis revealed essential amino acids within the transmembrane domain. Moreover, replication-competent mutant viruses were generated by randomization of 10 amino acids of the transmembrane domain. Of eight unique viruses, two contained only two amino acids in common with wild type and the remainder contained one or none within the randomized sequence. Although these mutant viruses formed normal size plaques, the entry-fusion complex did not co-purify with the mutant O3 proteins suggesting a less stable interaction. Thus, despite low specific sequence requirements, the transmembrane domain is sufficient for function in entry.
authors.affiliation: Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 33 North Drive, MSC 3210, Bethesda, MD 20892-3210, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Satheshkumar
authors.forename: James
authors.initials: J
authors.lastname: Chavre
authors.forename: Bernard
authors.initials: B
authors.lastname: Moss
mesh_terms: D019943:Amino Acid Substitution; D004252:DNA Mutational Analysis; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D014616:Vaccinia virus / Q000502:physiology*; D014760:Viral Fusion Proteins / Q000235:genetics / Q000378:metabolism*; D053586:Virus Internalization
chemical_list: D050505:Mutant Proteins; D014760:Viral Fusion Proteins
keywords: Entry–fusion complex; Membrane fusion; Mutagenesis; Poxvirus entry; Transmembrane protein